The Wall Street Journal's John Fund attended the Aspen Ideas Festival last week, and declared Bill Clinton the star of the show. Clinton "strode onto the stage of a huge music tent Saturday and received a standing ovation from thousands of well-heeled, overwhelmingly liberal festival attendees." Was it really "thousands" (as in two or more)? No matter, Fund is right: The audience gave Clinton a standing ovation just for turning up.

The former president looked fit. He had a nice tan and wore cowboy boots. He could have said anything—"If I were still president, I would have bombed Iran by now"—and the assembled bleeding-heart plutocrats, resting between spells of discussing their carbon footprints, would still have lapped it up.

As usual, Clinton was shrewdly gracious to his enemies. He applauded President Bush's policies on combating AIDS and malaria in Africa. This flattered the audience—whose minds were as closed on the subject of George W. Bush as any minds could be—that they, too, were intelligent and high-minded about the man; and that their loathing for everything else the president stands for is not a reflex but a considered view. "Yes, Bush is good on malaria. You have to give him that." Clinton's political genius resides in touches like this. It is something to see.

Yet Clinton was not the star of the show so far as I was concerned. I give that accolade to Karl Rove.

Almost everybody who stayed to listen to Rove on the festival's last day went there mainly in the hope that heavy equipment might fall on him from a great height. This was the same crowd that had gazed wide-eyed and enchanted at their beloved Bill. Why does Rove accept these invitations, one wondered on the way in? Possibly, he does it for fun. He gave every impression of having a good time. And, in fact, he ran rings round an audience that came not to praise him but in the hope that somebody might bury him.

Interviewed by the Aspen Institute's Walter Isaacson, Rove started with some lighthearted self-deprecation. Driving to Aspen, he said with a grin, he had stopped for a coffee. Returning from the men's room, he stood in line at the counter and heard a man, just alerted to his presence in the cafe, say, "I'd like to hit that son of a bitch." Later, he was accosted by the driver of "a very expensive Land Rover," who shouted "go home" and then drove off. Rove said he was too slow to answer that he was home—he was born in Denver—and to tell the moneyed outsider to get into his private jet and fly back to the East Coast. The man had disappeared before Rove could frame the thought, but it was a good reply after the fact, he said.

It was clever to combine modesty with a pointed jab at the crowd. Despite itself, the audience laughed and was disarmed. Even Clinton would have been impressed.

Rove is the archetypal eminence grise, the backroom planner, all tactics, poll findings, and sinister maneuverings, so it comes as a shock to hear him talk knowledgeably and with apparent conviction on policy. He had slides full of facts and numbers, not on trends in campaign demographics but on immigration, energy efficiency, greenhouse-gas emissions, and the like. He was engaging and very well prepared. He spoke like an unusually effective candidate for office, not a strategy nerd.

Asked about reducing the commitment of forces in Iraq, Rove said that the surge was temporary, to stabilize the situation and to get to a position where troops can be brought home. He cited the Baker-Hamilton Iraq Study Group report in support of the policy. He wouldn't be drawn into committing on a timetable, and he acknowledged that attacks on U.S. forces were up; but he said that the numbers of Iraqi victims of the insurgency were down and that conditions in Anbar province were much better than had seemed likely last year. Progress was being made. On the unpopularity of the al-Maliki government, he called for patience: It has not been in place very long, he said, and needs to be given a chance.

Later he was asked, twice, about a report in that day's New York Times that said that an opportunity to attack Al Qaeda's leaders in Pakistan had recently been allowed to slip by. Was the administration serious about trying to catch or kill Osama bin Laden and the others?

It seemed odd to press Rove hard on this—as though the White House did not have the strongest possible incentive to kill or capture bin Laden and his people.

Rove then dwelt at length on the Senate's recently aborted immigration reform, which the White House had backed. The plan aimed to balance tighter security at the border and behind it with a) easier entry for temporary workers and for immigrants with skills, and b) steps to regularize the status of the 12 million or so illegal immigrants in the U.S.

Rove argued that resistance to the bill was driven mainly by fear that the border could not be policed more effectively—so that the bill's "amnesty" for illegal workers already here would not be the last (any more than the amnesty of 1986 had been). But this was a misunderstanding, Rove said. Efforts to tighten the border had already been stepped up. Last year, authorities detained and returned 1.3 million illegal immigrants—far more, Rove said, than people most worried about the bill had imagined. The restricted flow of immigrants is already producing labor shortages.

He also described a 2005 experiment in border security, Operation Texas Hold 'Em, which concentrated on apprehending illegal Brazilian immigrants who were crossing at a particular section of the Texas border. As Rove related it, this was a no-expense-spared undertaking. Instead of releasing captured immigrants, often the standard practice, the policy was switched to detaining and deporting them. It was a success, he said, but at a cost; scaling it up for the whole border would be very expensive. Rove's point was that further tightening of the border—which the abandoned bill provided for—was not a hopeless endeavor. It could be done and had been done.

On energy, he seemed equally in command of his material. He made the case for the administration's "20 in 10" program, which aims to reduce use of petroleum by 20 percent in 10 years, urging a switch from the fleet-based corporate average fuel economy standards for passenger cars (which are set by Congress) to a weight-based standard (like the one administered by the Transportation Department for light trucks). This is less susceptible to gaming by vehicle manufacturers and less likely to confer a competitive advantage on foreign companies, which may have more small vehicles in their fleets. He also surprised the audience by saying that the United States was the only country in the world to reduce its greenhouse-gas emissions in 2006 (partly, as he noted, because of unusually favorable weather).

The administration's optimistic view that technology can painlessly solve the problems of climate change and energy security was, in fact, in tune with the ideas favored by most other speakers on energy at the conference. The case for greater reliance on nuclear power was not pressed hard: Bad idea, no need for it, was the view expressed at many panels. Even in Aspen's green-tinged intellectual environment, there was little support for a carbon tax—the simplest way to fold the external costs of carbon emissions into the price of energy.

Rove argued that a carbon tax would not be so simple. Adjusting the impact so that, for instance, it did not fall too heavily on people forced to drive long distances because of where they live would be complicated. He said that a carbon tax was not necessary, and many of the technology mavens brought in for the gathering (including Amory Lovins, doyen of energy-efficiency experts) seemed to agree. By this time, Rove's audience was listening attentively. Boundless faith in technology solutions with no growth penalty seems to unite Rove and Al Gore, unlikely as that might seem.

It amused me that Rove and Clinton both cited the United Kingdom as a country that is successfully curbing its carbon emissions and reaping a growth premium in return. Rove gave the credit to Margaret Thatcher for crushing the coal miners union and starting a big switch to nuclear. Clinton gave it to a drive for alternative fuels, which had also boosted growth and cut poverty. Neither was right, but Rove was closer: It was the post-Thatcher switch from coal to natural gas, not nuclear, that mainly brought emissions down. Britain has little to boast about on the alternative-fuels front, or for that matter, on poverty reduction.

Rove was given no ovation, just polite applause. But that was a far greater success than Clinton's ecstatic reception, and yet another reminder that one of the greatest assets in politics is to be underestimated.